Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A number of applications for mobile computing devices, such as mobile telephones, utilize location information. A variety of technologies exist for determining location information about mobile computing devices. One location technology is the Global Positioning System (GPS) technology, which involves processing signals from a number of satellites (typically 3 or 4) and determining location based on the processed signals.
GPS technology provides fairly accurate results, but can consume a great deal of power and so rapidly drains power of mobile computing devices. At some times, too few satellites are in range of a mobile device to enable GPS location of the mobile device. Other location systems involve use of triangulating radio (or other electromagnetic) waves, but these systems are not always accurate and may have significant environmental restrictions. For example, infrared or microwave systems are line of sight only and so may not be accurate for outdoor locations. Further, in some areas, radio wave-based triangulation systems may not have enough wave sources to enable triangulation.